Muscles
Muscle = Latin Musculus = “Little Mouse”
Function of Muscles –
1. Movement of Skeleton
2. Control of Openings ex: mouth, anus
3. Stabilize Joints & Maintain Posture
4. Produce Heat when cold
5. Facial Expressions ex: happy, sad, fearful
6. Protection ex: eyes, mouth, internal organs
Nomenclature – Naming of Muscles
1. Shape ex: deltoid upside-down delta
2. Number of Heads or points of attachment ex: bicep = 2 heads
3. Length Short = Brevis, Long = Longus
ex: extensor carpus radalis longus
4. Location
ex: biceps brachei – arm
biceps femoris – thigh
intercostal – between ribs
temporalis – over temporal bone
5. Attachments ex: sternocleidomastoid (sternum-clavicle-mastoid)
Function of Muscles –
1. Flexor & Extensor - fold and straighten
2. Adductor & Abductor – bring together and take away
3. Supinator & Pronator – palm up and palm down
Prime function of a muscle is to move or contract.
The Antagonist function is to relax
Attachment to Limbs –
Origins – proximal (nearest to midline) region of limb
Insertion – Distal (distance end away from midline) region of limb
Ex:
Origin Coracoid Process & Acromium
Biceps brachii
Insertion Proximal Radius
Histology of Muscles –
3 types
1. Smooth or Visceral – around hollow organs or tubes
2. Cardiac – heart
3. Skeletal or Striated – Attached to bones
These differ in structure, function and location.
Smooth or Visceral or Involuntary Muscle –
Made of single cells with a central nucleus and found in sheets held
together by connective tissue.
Largest Smooth Muscles = Uterus and Digestive tract – peristalsis - slow
rhythmic contractions
Greatest endurance = Pupil of eye, it is always working
Two muscles – radial and circular muscles
Smooth Muscle
Cardiac Muscle –
Tubular cells with central nuclei.
They are branched and have intercalated discs along the fibers that help
facilitate the spread of the contraction and have striations.
Intercalated disc
Nuclei
Intercalated discs also increase the strength of the connection
between cardiac muscle cells.
Cardiac Muscle
Skeletal Muscle –
Longest Muscle cells in the Sartorius 35cm or 14” long
Smallest Muscles in the Inner Ear 10u
Peripherally Multinucleated Cells make up fibers stronger than steel
Terms:
Sarcolemma “flesh” Cell membrane of a muscle cell
Sarcoplasm is the cytoplasm of muscle cells
Sarcomere is the functional unit of muscle contraction.
Actin and Myosin (sarcomere)
Myofilaments
Myofibrils
Muscle contract due to nerve impulse coming to sarcolema
Impulse
Sarcolema
Sarcolemic Reticulum
Ca++ released
This causes the actin and myosin to slide together
“ Sliding Filament Theory”
Figure 08.07
Figure 08.08
Figure 08.09a
Figure 08.09b
Muscles of the Body
How many muscles do you have?
It was 638 until 1996 when a new muscle was
found that connects from the orbit to the mandible
so now it is 639.
Muscle of Head
Levator Palpabra
Splenius Capitis
Trapezius
Muscles of Head
Muscles of the Jaw –
7. Temporalis
O – Squamous portion of Temporal Bone
I – Coronoid process of Mandible
A – Close Jaw
8. Masseter – “chewer”
O – Zygomatic Arch
I – Angle and Ramus of Mandible
A – Close Jaw
Levator Palpabra
Splenius Capitis
Trapezius
Big Muscles of Trunk
1. Trapezius – tapezoid shaped found superior posterior
O – Occipital Bone & Ligamentum Nuchae (attaches to all the
spines of Thoracic & Cervical vertebrae)
I – Spine of Scapula & Lateral 1/3 of Clavicle
A – Adduct scapula, depress scapula, raise scapula & extend head
Head
Ligamentum
Nuchae
Clavicle
Scapula
2. Latissimus Dorsi –”Broad” lower back - Inferior Posterior
O – Thoraco Lumbar Faccia
I – Anterior Intertubercular Groove of Humerus
A – Medial Rotate Humerus, Adduct Humerus, Depress Humerus
Acromium
3. Rotator Cuff - Connects Scapula to Humerus
Four Muscles –
Scapula
1. Supraspinous Muscle
2. Infraspinous Muscle
3. Subscapularis Muscle
4. Teris Minor
O – Scapula
I – Proximal Humerus
A – Adduct & Abduct Humerus, rotate Humerus medial & lateral
Humerus
Rotator
Cuff
Ligamentum nuchae
Aponeurosis
Arm & Forearm –
Muscles of the arm are for strength
Muscles of the forearm are for dexterity
Arm Muscles – Between shoulder and elbow
Biceps – 2 heads or points of origin (short and long head)
O – 1. Coracoid Process short head
2. Lip of Glenoid Fossa long head
I – Radial Tuberosity
A – Powerful Supinator (Hold a bowl of soup)
Flexor
Figure 08.21
Triceps – 3 heads – Posterior arm
1 on Scapula , 2 on proximal end of Humerus
O – Infra Glenoid Tubercle
Proximal Humerus stretching from medial to lateral
I – Olecranon Process of the Ulna (Elbow)
A – Extends forearm & stabilizes elbow joint
Forearm Muscles Brachio Radialis Muscles – Gives shape to forearm
Anterior Muscles flexor of wrist and fingers
Posterior Muscles Extensor of wrist and Fingers
Thenar Eminence – Large muscle at the base of the thumb
Figure 08.22
Anterior Superior Trunk Muscles -
1. Pectoralis Major – Chest Muscles
O – Sternum, Medial Clavicle, 2-6 Costal Cartilage
I – Outer lip of Intertubercular Groove of Humerus
A – Adduct & Medial Rotate Humerus
2. Deltoid – Gives shape to the shoulder
O – Lateral Clavicle & spine of Scapula
I – Deltoid Tuberosity of Humerus
A – Abduct Humerus and assist Bicep and Tricep
Abdominal Muscles –
All anterior muscles for the support and protection of abdominal & pelvic
viscera. Contraction of these muscles flexes vertebral column.
1. Rectus Abdominus – Rectus = “straight” – major visible abdominal
muscles known as a “six-pack”.
O – 5,6 & 7 Costal Cartilage and Xiphoid Process
I – Pubic Bone & Pubic Symphysis
Linea Alba – “white line” No blood vessels just connective tissue
Costal
Cartilage
Sternum
Wrapped in aponeurosis of the External Obliques,
Internal Obliques & Transverse
Linea Alba
Linea
Alba
E.O.
Rectus
Abdominus
Trans
I.N.
Rectus Abdominus
Pubic Bone
External Obliques – Very important muscles and aponeurosis
O – Lower Ribs
I - Linea Alba
Action -
1. Support & Potect Pelvic Viscera
2. Flex Vertebral Column
3. Aids in Breathing
4. Aids in Vomiting
5. Aids in Defecating
6. Aids in Childbirth
7. Used for laughing, coughing and sneezing
Folded bottom of aponeuroces forms Inguinal Canal. Testes descend
through this canal after birth in males.
Inguinal Hernia – Intestines can get stuck in canal and get squeezed
Muscles of the Hip -
19 muscles in hip
Function - Flex & Extend, Adduct & Abduct, Circumduct
Two Groups of Muscles –
1. Gluteal Muscles – Posterior Pelvis / Buttock
Give shape to posterior pelvis
Humans have the largest Gluteal Muscles
Females have fat pads on top of the muscle
3 Muscles – Gluteal Maximus, Gluteal Medius and
Gluteal Minimus
O – Ilium I – Posterior Ilium, Ileotibal band &
Greater Trochanter of Femur
Figure 08.26
2. Anterior Thigh Muscles –
1. Sartorius – called the “Taylor’s Muscle” – Let you sit cross
legged.
O – Anterior Iliac Spine
I – Medial Proximal Tibia
A – Flex Hip Joint & Flex Knee Joint
2. Quadricep – 4 muscles
They are held together by Faccia Lata a tough fibrous wrapping
1. Rectus Femoris
2. Vastus Lateralis
3. Vastus Intermedus
4. Vastus Medialis
O – Ilium & Proximal Femur I – Quadriceps Tendon to Patella
Tendon and Tibial Tuberosity.
A – Extends Leg
Figure 08.25
iliotibial band
Medial Thigh Muscle – Grailis “slender”
O – Pubic Bone I – Medial Proximal Tibia A – Adduct Thigh & Flex Knee
Posterior Thigh Muscles –
Hamstring
-
1. Biceps Femoris
2. Semimembranosus
3. Semitendenosus
O – ischium I - Proximal Medial Tibia A - Extend Hip & Flex knee
Figure 08.27
Anterior Leg –
Front of Tibia has no muscles just periosteum containing nerves that’s why
is hurts so much when you hit you shin.
Tibilas Anterior – Along sides of tibia connects to Dorum “top” of foot so you
can pull you foot up.
Posterior Leg –
1. Gastrocnemius – superficial - gives shape to calf, large in humans
O – epicondyles of Femur I – Calcaneus (heel) via the Achilles Tendon
A – Extends foot called Plantar Flexon “plant on ground”
2. Soleus – deep muscle –
O – Proximal Fibia & Fibula I – Achilles Tendon A – Plantar Flexon
Figure 08.28
Figure 08.30
Figure 08.15
Figure 08.16